Do not update RBS file if the signature nothing changed

lib/rbs_rails/cli.rb

@@ -126,7 +126,7 @@ def generate_single_model(klass, dep_builder) #: bool
       path.dirname.mkpath
 
       sig = RbsRails::ActiveRecord.class_to_rbs(klass, dependencies: dep_builder.deps)
-      path.write sig
+      Util::FileWriter.new(path).write sig
       dep_builder.done << klass.name
 
       true
@@ -137,7 +137,7 @@ def generate_path_helpers #: void
       path.dirname.mkpath
 
       sig = RbsRails::PathHelpers.generate
-      path.write sig
+      Util::FileWriter.new(path).write sig
     end
 
     def create_option_parser #: OptionParser

lib/rbs_rails/util.rb

@@ -1,3 +1,5 @@
+require_relative 'util/file_writer'
+
 module RbsRails
   module Util
     MODULE_NAME = Module.instance_method(:name) #: UnboundMethod

lib/rbs_rails/util/file_writer.rb

@@ -0,0 +1,22 @@
+module RbsRails
+  module Util
+    # To avoid unnecessary type reloading by type checkers and other utilities,
+    # FileWriter modifies the target file only if its content has been changed.
+    class FileWriter
+      attr_reader :path  #: Pathname
+
+      # @rbs path: Pathname
+      def initialize(path) #: void
+        @path = path
+      end
+
+      def write(content) #: void
+        original_content = path.read rescue nil
+
+        if original_content != content
+          path.write(content)
+        end
+      end
+    end
+  end
+end

sig/rbs_rails/util/file_writer.rbs

@@ -0,0 +1,16 @@
+# Generated from lib/rbs_rails/util/file_writer.rb with RBS::Inline
+
+module RbsRails
+  module Util
+    # To avoid unnecessary type reloading by type checkers and other utilities,
+    # FileWriter modifies the target file only if its content has been changed.
+    class FileWriter
+      attr_reader path: Pathname
+
+      # @rbs path: Pathname
+      def initialize: (Pathname path) -> void
+
+      def write: (untyped content) -> void
+    end
+  end
+end

sig/rbs_rails/utils/file_writer.rbs

@@ -0,0 +1,4 @@
+# Generated from lib/rbs_rails/utils/file_writer.rb with RBS::Inline
+
+module RbsRails
+end

test/rbs_rails/util/file_writer_test.rb

@@ -0,0 +1,49 @@
+require 'test_helper'
+require 'tmpdir'
+require_relative '../../../lib/rbs_rails/util/file_writer'
+
+class FileWriterTest < Minitest::Test
+  def setup
+    @temp_dir = Pathname.new(Dir.mktmpdir('file_writer_test'))
+  end
+
+  def teardown
+    FileUtils.rm_rf(@temp_dir) if @temp_dir
+  end
+
+  def test_write_on_file_not_found
+    file_path = @temp_dir / 'non_existent_file.rbs'
+    file_writer = RbsRails::Util::FileWriter.new(file_path)
+
+    file_writer.write("content")
+
+    assert file_path.exist?
+    assert_equal "content", file_path.read
+  end
+
+  def test_write_on_changed
+    file_path = @temp_dir / 'test_file.rbs'
+    file_path.write("old content")
+
+    file_writer = RbsRails::Util::FileWriter.new(file_path)
+
+    file_writer.write("new content")
+
+    assert_equal "new content", file_path.read
+  end
+
+  def test_write_on_not_changed
+    content = "unchanged content"
+    mtime = Time.now - 10
+
+    file_path = @temp_dir / 'test_file.rbs'
+    file_path.write(content)
+    file_path.utime(mtime, mtime)
+
+    file_writer = RbsRails::Util::FileWriter.new(file_path)
+    file_writer.write(content)
+
+    assert_equal content, file_path.read
+    assert_equal mtime, file_path.mtime
+  end
+end